• Please note that Audiokarma will be offline briefly for updates early on Monday morning, September 28th.

Ipod motor drive how to.

edd9000

edd9000

Don't Panic!
Inspired by http://www.altmann.haan.de/turntable/ with a little more detail.

First step is get audacity, its free. http://audacity.sourceforge.net/

Once installed, go to generate, then tone, then use these settings

tone-settings.jpg


60hz as its the mains frquency. 0.95 so it doesnt clip, and 1800 second for 30mins, longer than one side of an lp.

Click OK

Next go to edit, Duplicate.

should look like this:

tone2.jpg


Click the time tool, its the one at the top left with 2 arrow on a line. Then drag the bottom wave 90 degrees to the left so it looks like this:

tone3.jpg


Now click audio track to the left of one of the waves and select make stereo.

It probably worth setting to 16bit as well. this is under audiotrack then select sample format.

Now file, export as wav, and there you have it, one 60hz wave file.
 
Register to hide this ad
Now for the hard ware.

I have been using this amp http://www.parts-express.com/pe/showdetl.cfm?Partnumber=300-380

You want a 12v stepper motor, it just so happens these have about a 4ohm coil, like a speaker so the amp can drive them directly.

Mine came off ebay, about $7, but here is an example http://www.allelectronics.com/make-a-store/item/SMT-120/ROTARY-STEPPER-MOTOR/1.html

The motor will have 4 leads, use an ohm meter to find the pairs which are connected to each other, then hook them up to the amp:

motor.jpg


Reversing one pair will reverse the motor. Try reversing both, and swapping channels, ive found all work, but one may vibrate less.

Now all you have to do is play the wav from your ipod into the amp, turn the ipod up to full, and bring the volume up on the amp untill the motor spins.

This system brings my 20 odd pound platter up to speed in 3 seconds or so.

To run a standard 110v motor, that you will find in a TT like say a linn or rega, use a 110v to 9v stepdown transformer and run it backwards, a 30va toroid will do the job.
 
similost said:
So is this just a geeky kind of experiment, or is there a real world use for doing this?
Click to expand...

A few advantages.

Main one is variable speed. vary the Frequecy of the signal and you can fine tune the rpm of the table. Also means you dont have to be presice with belt or pulleys, just adjust the frequency.

It lets you reduce the voltage of the motor once up to speed. this will reduce vibration. you could do this manualy, or put slope on the wave form.

It lets you generate 2 phases at exactly 90 degrees apart, and fine tune the phase for lower vibration. This is better than just using a capacitor to fake the second phase.

All the above should result in a lower vibration and more precise motor than before with minimal cost. Compare this to a vpi SDS at $1000, it does basicaly the same, just in a more user friendly manor.
 
thats way cool!! you could even condense the assembly size using the T-amp module now avail from PE!
 
This thread is fantastic!

Out of curiosity, How smooth does your motor run? Can you hear any vibration or sense anything if you touch it?
 
Last edited:
You must log in or register to reply here.
Back
Top Bottom